Natural history of preexisting AAV5 antibodies in adults with hemophilia B during the lead-in of the etranacogene dezaparvovec phase 3 study

= 0.0065). For participants with detectable anti-AAV5 NAbs and IgG, there was a high correlation of titers at each visit (median r = 0.96; range: 0.92-0.99). IgM anti-AAV5 antibodies were detectable in only 9% of participants, and seroconversion was infrequent. In conclusion, AAV5 NAb test results were consistent over 6 months, which informs the timing of NAb screening when considering gene therapy for hemophilia B.